backtop


Print 76 comment(s) - last by clarkn0va.. on Jan 8 at 2:01 PM

Mazda is already discussing Skyactiv 3 as well

Mazda only recently started introducing its Skyactiv engines to its different vehicle models, but the automaker is already talking about the upcoming Skyactiv 2 -- and even Skyactiv 3 -- engines for the next decade and beyond. 
 
According to a new report from Automotive News, Mazda plans to gain 30 percent better fuel economy with its Skyactiv 2 engines, which are expected to have a 2020 release date. A 30 percent improvement in fuel economy would make the already impressive Mazda3 rise from 29/41 mpg (city/highway) in its more efficient trim to 38/53 on regular unleased gasoline.
 

2014 Mazda3

Mazda plans to achieve this 30 percent increase in fuel economy by improving the internal combustion of the Skyactiv 2 engines. More specifically, the Skyactiv 2 engine's compression ratio would be bumped up to 18:1 from a current level of 14:1. 
 
This higher compression is able to reach the same combustion temperature as the current engines, but with a leaner mix of fuel -- meaning improved fuel economy. 
 
The Skyactiv 2 engines will utilize homogeneous charge compression ignition (HCCI), which compresses the fuel-air mixture to a high enough pressure and temperature that it ignites by itself without needing a spark. This allows for more complete fuel combustion and lower nitrogen oxide emissions.
 
However, the Automotive News report indicates that HCCI won't come easy. Engineers must first expand the range of engine speeds for HCCI specifically, because the engine revving too quickly can result in a misfire due to the high number of revolutions, and if revved too slowly, it can misfire due to low temperatures.


2.0-liter Skyactiv four-cylinder engine
 
Aside from that, engine cooling and the engine's tendency to behave differently based on the use of different fuels need to be figured out.
 
The main goal with Skyactiv 2 is to meet European carbon dioxide emissions standards of 95 grams per kilometer in 2020, but Mazda is looking even further ahead at meeting Europe's standards of 65 grams per kilometer in 2025 with Skyactiv 3. 
 
Mazda didn't go into great detail about Skyactiv 3, but the automaker plans to make more energy available for powering the wheels by limiting the fluctuation of heat in the combustion chamber and reduce losses from exhaust and cooling. Mazda hopes to reach well-to-wheel carbon dioxide emissions with Skyactiv 3 that rival electric vehicles.
 
Mazda first introduced Skyactiv engines to the U.S. market in 2011, starting with the Mazda3 sedan. Since then, they've been added to the Mazda6 sedan and CX-5 crossover.
 
Mazda has been trying to bring the Skyactiv-D diesel engine to the U.S. via the Mazda6, and was supposed to have achieved this by the second half of 2013. However, in September of last year, it was announced that delays in emissions testing has pushed that timetable to late spring of 2014.

Source: Automotive News



Comments     Threshold


This article is over a month old, voting and posting comments is disabled

RE: Hmmm
By TheEquatorialSky on 1/6/2014 2:28:44 PM , Rating: 2
The more gears you have, the longer you can keep an engine at its max BSFC. There are manual transmissions with 6+ speed (especially in commercial trucking), but shifting every 500-1000rpm ain't fun.

Manuals can get hybrid-like city MPG, but only by "pulse and gliding." The engine needs to be operated at max BSFC (generally peak torque) and shut off when at speed. Rinse and repeat. Hybrids get excellent city MPG mostly through its motor, not its automatic transmission.

Also, not all automatics are made equal. The Prius transmission is dead simple and reliable.


RE: Hmmm
By lucyfek on 1/6/2014 3:28:38 PM , Rating: 2
Sure, when you add hybrid drive than AT may make sense (even then probably dual clutch as torque converter is pure waste until locked). And shifting every 500 rmps IS fun (not that I really think/notice it any more than traffic in front of me, btw I never really go pass 3000 so shifting every 1000 seems like a "spirited" driving).
Also, for non-hybrid cars maximum BSFC is - again - more closely related to performance than max mpg - I know that driving 40mph in 5th (highest for my car) won't get me best acceleration but no AT will beat the mpg (none of these would shift into highest gear yet being programmed for performance that matches somebody's else expectations, regardless of time, mood, snow on the road etc). It's easy to observe this mpg/rpm relation through odb2 - I bet that coasting to the red light in neutral is very bad from the point of view of BSFC yet gets great mpg (regular car with AT will keep engine revved up and waste more gas in the process, regardless of how many speeds the AT had).
Also, speaking of hybrids I'm not sure if any of these shuts down the engine while cruising at highway speeds (unlikely) and I'm not sure if disengaging AT at speed is great for them (I know it'll not break right away;).
Anyway, the moment I have no manual option in standard vehicle (not a performance car) I surely go for hybrid as all control over the drive-train and economy of initial purchase has already been impaired.


RE: Hmmm
By TheEquatorialSky on 1/6/2014 4:20:03 PM , Rating: 2
1. More gear sets make sense hybrid or not.

2. Shifting frequently is not fun. Truckers w/ 13spd. transmissions shift every 250rpm. Listen to them and you'll hear them shift >5x (!) before crossing an intersection from a stop. No thank you.

3. Max BSFC is the most efficient conversion of gasoline to HP. Hybrid/non-hybrid is irrelevant.

4. Modern ATs utilize very tall top gear ratios, which suck for accelerating. Shifting is near instantaneous, so there is no downside.

5. It's illegal to coast in neutral. Automatics can theoretically do so... some DCT actually do. Hybrids certainly do below a certain speed.


"This is from the DailyTech.com. It's a science website." -- Rush Limbaugh














botimage
Copyright 2014 DailyTech LLC. - RSS Feed | Advertise | About Us | Ethics | FAQ | Terms, Conditions & Privacy Information | Kristopher Kubicki